The invention relates to a grate trough as part of a grate for a plant for the thermal treatment of waste.
As is known, for example, from EP-B-0 713 056, a grate has a plurality of, as a rule three to five, grate elements which are arranged one behind the other and each comprise a plurality of grate block rows arranged one behind the other in a stairlike manner. A fixed grate block row is followed in each case by a movable grate block row which exerts a pushing and shearing action on the waste material located on the grate. Each grate block row is formed by a plurality of grate blocks which are suspended next to one another on a block holding tube and which are firmly connected to one another. The block holding tubes of the movable grate block rows are carried by brackets which are fastened on a movable grate carriage. Brackets, which are mounted on a fixed block, are also provided for the block holding tubes of the fixed grate block rows. This block is connected to side walls of a grate trough which forms the lower part of the respective grate element. The movable grate carriage is also supported on the side walls. A front and a rear frontal wall are arranged at right angles to the side walls of the grate trough and are welded to the side walls. The adjacent frontal walls of individual grate elements are screwed to one another. For an exact alignment of the block holding tubes, an exact arrangement of the brackets and of the supporting surfaces for the grate carriage is indispensable. The walls of the grate trough must be aligned exactly with one another. After the wall edges butting on one another have been welded together, the adverse effects of the weld seam distortion must be rectified, the block or its bearing surface for the brackets must be oriented exactly and the brackets must be positioned and welded on accurately.
The object of the present invention is to provide a grate trough which is simple and cost-effective in terms of production and which makes it possible to mount the grate element in a simple way.
Pursuant to this object, and others which will become apparent hereafter, one aspect of the present invention resides in a grate trough as part of a grate element for a grate which is provided for a plant for thermal treatment of waste, which grate has a plurality of grate elements arranged behind one another. Each grate element comprises a plurality of fixed and a plurality of movable grate block rows which are arranged so as to follow one another alternately and which are formed in each case from a plurality of grate blocks suspended next to one another on a block holding element and connected firmly to one another. The grate trough forms a carrying element for the block holding elements of the fixed grate block rows and support for a movable grate carriage carrying the block holding elements of the movable grate block rows. The grate trough comprises sidewalls extending in a longitudinal direction of the grate and a front and rear frontal wall. The frontal walls are welded to the sidewalls so as to be at right angles to the sidewalls. The sidewalls and the frontal walls have projections and recesses which engage into one another.
Since the frontal walls and the side walls have at their junction projections and recesses which engage one into the other, the grate trough walls are arranged and welded together in an exact position relative to one another, without the walls being capable of being displaced relative to one another. The length and width of the grate trough remains constant. The weld seam lines extending along the wall edges are offset relative to one another as a result of the projections and recesses engaging one into the other, with the result that the weld seam distortion and the weld seam stress are minimized. No additional work is necessary for aligning the grate trough walls or additional parts carrying the block holding tubes. The block holding tubes for the fixed grate block rows can be arranged directly in recesses of the side walls.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, and specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.